1 //===-- RuntimeDyld.h - Run-time dynamic linker for MC-JIT ------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // Interface for the runtime dynamic linker facilities of the MC-JIT. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_EXECUTIONENGINE_RUNTIMEDYLD_H 15 #define LLVM_EXECUTIONENGINE_RUNTIMEDYLD_H 16 17 #include "JITSymbolFlags.h" 18 #include "llvm/ADT/StringRef.h" 19 #include "llvm/Support/Memory.h" 20 #include <memory> 21 22 namespace llvm { 23 24 namespace object { 25 class ObjectFile; 26 template <typename T> class OwningBinary; 27 } 28 29 class RuntimeDyldImpl; 30 class RuntimeDyldCheckerImpl; 31 32 class RuntimeDyld { 33 friend class RuntimeDyldCheckerImpl; 34 35 RuntimeDyld(const RuntimeDyld &) = delete; 36 void operator=(const RuntimeDyld &) = delete; 37 38 protected: 39 // Change the address associated with a section when resolving relocations. 40 // Any relocations already associated with the symbol will be re-resolved. 41 void reassignSectionAddress(unsigned SectionID, uint64_t Addr); 42 public: 43 44 /// \brief Information about a named symbol. 45 class SymbolInfo : public JITSymbolBase { 46 public: 47 SymbolInfo(std::nullptr_t) : JITSymbolBase(JITSymbolFlags::None), Address(0) {} 48 SymbolInfo(uint64_t Address, JITSymbolFlags Flags) 49 : JITSymbolBase(Flags), Address(Address) {} 50 explicit operator bool() const { return Address != 0; } 51 uint64_t getAddress() const { return Address; } 52 private: 53 uint64_t Address; 54 }; 55 56 /// \brief Information about the loaded object. 57 class LoadedObjectInfo { 58 friend class RuntimeDyldImpl; 59 public: 60 LoadedObjectInfo(RuntimeDyldImpl &RTDyld, unsigned BeginIdx, 61 unsigned EndIdx) 62 : RTDyld(RTDyld), BeginIdx(BeginIdx), EndIdx(EndIdx) { } 63 64 virtual ~LoadedObjectInfo() {} 65 66 virtual object::OwningBinary<object::ObjectFile> 67 getObjectForDebug(const object::ObjectFile &Obj) const = 0; 68 69 uint64_t getSectionLoadAddress(StringRef Name) const; 70 71 protected: 72 virtual void anchor(); 73 74 RuntimeDyldImpl &RTDyld; 75 unsigned BeginIdx, EndIdx; 76 }; 77 78 /// \brief Memory Management. 79 class MemoryManager { 80 public: 81 virtual ~MemoryManager() {}; 82 83 /// Allocate a memory block of (at least) the given size suitable for 84 /// executable code. The SectionID is a unique identifier assigned by the 85 /// RuntimeDyld instance, and optionally recorded by the memory manager to 86 /// access a loaded section. 87 virtual uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment, 88 unsigned SectionID, 89 StringRef SectionName) = 0; 90 91 /// Allocate a memory block of (at least) the given size suitable for data. 92 /// The SectionID is a unique identifier assigned by the JIT engine, and 93 /// optionally recorded by the memory manager to access a loaded section. 94 virtual uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment, 95 unsigned SectionID, 96 StringRef SectionName, 97 bool IsReadOnly) = 0; 98 99 /// Inform the memory manager about the total amount of memory required to 100 /// allocate all sections to be loaded: 101 /// \p CodeSize - the total size of all code sections 102 /// \p DataSizeRO - the total size of all read-only data sections 103 /// \p DataSizeRW - the total size of all read-write data sections 104 /// 105 /// Note that by default the callback is disabled. To enable it 106 /// redefine the method needsToReserveAllocationSpace to return true. 107 virtual void reserveAllocationSpace(uintptr_t CodeSize, 108 uintptr_t DataSizeRO, 109 uintptr_t DataSizeRW) {} 110 111 /// Override to return true to enable the reserveAllocationSpace callback. 112 virtual bool needsToReserveAllocationSpace() { return false; } 113 114 /// Register the EH frames with the runtime so that c++ exceptions work. 115 /// 116 /// \p Addr parameter provides the local address of the EH frame section 117 /// data, while \p LoadAddr provides the address of the data in the target 118 /// address space. If the section has not been remapped (which will usually 119 /// be the case for local execution) these two values will be the same. 120 virtual void registerEHFrames(uint8_t *Addr, uint64_t LoadAddr, 121 size_t Size) = 0; 122 virtual void deregisterEHFrames(uint8_t *addr, uint64_t LoadAddr, 123 size_t Size) = 0; 124 125 /// This method is called when object loading is complete and section page 126 /// permissions can be applied. It is up to the memory manager implementation 127 /// to decide whether or not to act on this method. The memory manager will 128 /// typically allocate all sections as read-write and then apply specific 129 /// permissions when this method is called. Code sections cannot be executed 130 /// until this function has been called. In addition, any cache coherency 131 /// operations needed to reliably use the memory are also performed. 132 /// 133 /// Returns true if an error occurred, false otherwise. 134 virtual bool finalizeMemory(std::string *ErrMsg = nullptr) = 0; 135 136 private: 137 virtual void anchor(); 138 }; 139 140 /// \brief Symbol resolution. 141 class SymbolResolver { 142 public: 143 virtual ~SymbolResolver() {}; 144 145 /// This method returns the address of the specified function or variable. 146 /// It is used to resolve symbols during module linking. 147 virtual SymbolInfo findSymbol(const std::string &Name) = 0; 148 149 /// This method returns the address of the specified symbol if it exists 150 /// within the logical dynamic library represented by this 151 /// RTDyldMemoryManager. Unlike getSymbolAddress, queries through this 152 /// interface should return addresses for hidden symbols. 153 /// 154 /// This is of particular importance for the Orc JIT APIs, which support lazy 155 /// compilation by breaking up modules: Each of those broken out modules 156 /// must be able to resolve hidden symbols provided by the others. Clients 157 /// writing memory managers for MCJIT can usually ignore this method. 158 /// 159 /// This method will be queried by RuntimeDyld when checking for previous 160 /// definitions of common symbols. It will *not* be queried by default when 161 /// resolving external symbols (this minimises the link-time overhead for 162 /// MCJIT clients who don't care about Orc features). If you are writing a 163 /// RTDyldMemoryManager for Orc and want "external" symbol resolution to 164 /// search the logical dylib, you should override your getSymbolAddress 165 /// method call this method directly. 166 virtual SymbolInfo findSymbolInLogicalDylib(const std::string &Name) = 0; 167 private: 168 virtual void anchor(); 169 }; 170 171 /// \brief Construct a RuntimeDyld instance. 172 RuntimeDyld(MemoryManager &MemMgr, SymbolResolver &Resolver); 173 ~RuntimeDyld(); 174 175 /// Add the referenced object file to the list of objects to be loaded and 176 /// relocated. 177 std::unique_ptr<LoadedObjectInfo> loadObject(const object::ObjectFile &O); 178 179 /// Get the address of our local copy of the symbol. This may or may not 180 /// be the address used for relocation (clients can copy the data around 181 /// and resolve relocatons based on where they put it). 182 void *getSymbolLocalAddress(StringRef Name) const; 183 184 /// Get the target address and flags for the named symbol. 185 /// This address is the one used for relocation. 186 SymbolInfo getSymbol(StringRef Name) const; 187 188 /// Resolve the relocations for all symbols we currently know about. 189 void resolveRelocations(); 190 191 /// Map a section to its target address space value. 192 /// Map the address of a JIT section as returned from the memory manager 193 /// to the address in the target process as the running code will see it. 194 /// This is the address which will be used for relocation resolution. 195 void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress); 196 197 /// Register any EH frame sections that have been loaded but not previously 198 /// registered with the memory manager. Note, RuntimeDyld is responsible 199 /// for identifying the EH frame and calling the memory manager with the 200 /// EH frame section data. However, the memory manager itself will handle 201 /// the actual target-specific EH frame registration. 202 void registerEHFrames(); 203 204 void deregisterEHFrames(); 205 206 bool hasError(); 207 StringRef getErrorString(); 208 209 /// By default, only sections that are "required for execution" are passed to 210 /// the RTDyldMemoryManager, and other sections are discarded. Passing 'true' 211 /// to this method will cause RuntimeDyld to pass all sections to its 212 /// memory manager regardless of whether they are "required to execute" in the 213 /// usual sense. This is useful for inspecting metadata sections that may not 214 /// contain relocations, E.g. Debug info, stackmaps. 215 /// 216 /// Must be called before the first object file is loaded. 217 void setProcessAllSections(bool ProcessAllSections) { 218 assert(!Dyld && "setProcessAllSections must be called before loadObject."); 219 this->ProcessAllSections = ProcessAllSections; 220 } 221 222 private: 223 // RuntimeDyldImpl is the actual class. RuntimeDyld is just the public 224 // interface. 225 std::unique_ptr<RuntimeDyldImpl> Dyld; 226 MemoryManager &MemMgr; 227 SymbolResolver &Resolver; 228 bool ProcessAllSections; 229 RuntimeDyldCheckerImpl *Checker; 230 }; 231 232 } // end namespace llvm 233 234 #endif 235
